• International Journal of Korean Welding Society
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• v.3 no.2
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• pp.29-39
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• 2003

The durability and reliability of thermal barrier coatings (TBCs) play an important role in the service reliability, availability and maintainability (RAM) of hot­section components in advanced turbine engines for aero and utility applications. Photostimulated luminescence spectroscopy (PSLS) and electrochemical impedance spectroscopy (EIS) are being concurrently developed as complimentary non­destructive evaluation (NDE) techniques for quality control and life­remain assessment of TBCs. This paper overviews the governing principles and applications of the luminescence and the impedance examined in the light of residual stress, phase constituents and resistance (or capacitance) in TBC constituents including the thermally grown oxide (TGO) scale. Results from NDE by PSLS and EIS are discussed and related to the microstructural development during high temperature thermal cycling, examined by using a variety of microscopic techniques including focused ion beam (FIB) in­situ lift­out (INLO), transmission and scanning transmission electron microscopy (TEM and STEM).

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4002-4018
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• 2023

An integrated neutron interrogation system has been developed for non-destructive assay of highly-radioactive special nuclear materials, to accumulate knowledge of the method through developing and using it. The system combines a differential die-away (DDA) measurement system for the quantification of nuclear materials and a prompt gamma-ray analysis (PGA) system for the detection of neutron poisons which disturb the DDA measurements; a common D-T neutron generator is used. A special care has been taken for the selection of materials to reduce the background gamma rays produced by the interrogation neutrons. A series of measurements were performed to test the basic performance of the system. The results show that the DDA system can quantify plutonium of as small as 20 mg and it is not affected by intense neutron background up to 1.57 × 10⁷ s^-1 and gamma ray of 4.43 × 10¹⁰ s^-1. The gamma-ray background counting rate at the PGA detector was reduced down to 3.9 × 10³ s^-1 even with the use of the D-T neutron generator. The test measurements show that the PGA system is capable of detecting 0.783 g of boron and about 86.8 g of gadolinium in 30 min.

• Journal of Korean Society for Quality Management
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• v.8 no.2
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• pp.15-22
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• 1980

This paper deals with the problem of determining a minimum cost sampling inspection plan for a single destructive testing by attribute. The cost for inspection lot is constructed by following three cost factors: (1) cost of inspection, (2) cost of accepted defective, (3) cost of rejected lot Using Hald's Bayesian approach in a single non-destructive testing, procedure's for finding the minimum cost single destructive sampling inspection plan by attribute are given. Assuming the uniform distribution as a prior-distribution and using numerical analysis by computer, a minimum cost single destructive sampling inspection plan by attribute for several lot sizes, unit cost, destructive testing cost, and salvage cost is given.

• Current Optics and Photonics
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• v.4 no.1
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• pp.31-43
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• 2020

The feasibility of the application of terahertz electromagnetic waves in the diagnosis of prostate cancer was examined. Four samples of incomplete cancerous prostatic paraffin-embedded tissues were examined using terahertz spectral imaging (TPI) system and the results obtained by comparing the absorption coefficient and refractive index of prostate tumor, normal prostate tissue and smooth muscle from one of the paraffin tissue masses examined were reported. Three hundred and sixty cases of absorption coefficients from one of the paraffin tissues examined were used as raw data to classify these three tissues using the Principal Component Analysis (PCA) and Least Squares Support Vector Machine (LS-SVM). An excellent classification with an accuracy of 92.22% in the prediction set was achieved. Using the distribution information of THz reflection signal intensity from sample surface and absorption coefficient of the sample, an attempt was made to use the TPI system to identify the boundaries of the different tissues involved (prostate tumors, normal and smooth muscles). The location of three identified regions in the terahertz images (frequency domain slice absorption coefficient imaging, 1.2 THz) were compared with those obtained from the histopathologic examination. The tissue tumor region had a distinctively visible color and could well be distinguished from other tissue regions in terahertz images. Results indicate that a THz spectroscopy imaging system can be efficiently used in conjunction with the proposed advanced computer-based mathematical analysis method to identify tumor regions in the paraffin tissue mass of prostate cancer.

• Food Science and Industry
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• v.55 no.1
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• pp.2-22
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• 2022

Near-infrared spectroscopy (NIRS) is one of the representative non-destructive and eco-friendly analysis methods used for rapid analysis of various ingredients in the food industry. To develop analysis model with NIRS, Chemometrics are applied after pre-treatment of spectrum. Many studies have been reviewed on the analysis of general and functional components for agricultural and livestock products. In the case of livestock products, some studies have been conducted for on-line analysis. This study investigated results on various samples and component applying near-infrared spectroscopy. Furthermore, the results according to sample condition were compared. It was confirmed that NIRS is applied to various fields in the food industry.

• Structural Engineering and Mechanics
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• v.46 no.5
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• pp.615-627
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• 2013

One of the most common defects in reinforced concrete bridge decks is corrosion of steel reinforcing bars. This invisible defect reduces the deck stiffness and affects the bridge's serviceability. Regular monitoring of the bridge is required to detect and control this type of damage and in turn, minimize repair costs. Because the corrosion is hidden within the deck, this type of damage cannot be easily detected by visual inspection and therefore, an alternative damage detection technique is required. This research develops a non-destructive method for detecting reinforcing bar corrosion. Experimental modal analysis, as a non-destructive testing technique, and finite element (FE) model updating are used in this method. The location and size of corrosion in the reinforcing bars is predicted by creating a finite element model of bridge deck and updating the model characteristics to match the experimental results. The practicality and applicability of the proposed method were evaluated by applying the new technique to a two spans bridge for monitoring steel bar corrosion. It was shown that the proposed method can predict the location and size of reinforcing bars corrosion with reasonable accuracy.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.425-432
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• 2003

The joint treatment of concrete is one of the technical problems in concrete constructions. Joints created with concrete constructions result in serious weakness in the aspects of both structural and water-barrier function. The radar and the infrared thermography method have been used for the non-destructive inspection of several construction joints of concrete structures in this study. The advantages and limitations of these methods are investigated for non-destructive inspection on construction joints of concrete columns. It can be shown that the detecting precision of construction joints using these methods is improved if radar analysis is carried out with a simulation analysis. In case of the infrared thermography method, the shape of construction joints can be also detected when heating is performed before testing. As the result, it has been verified that the construction joints, difficult to be detected by visual inspection, could be inspected effectively in broad areas at short period of time when these two methods are applied.

• 보존과학연구
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• s.35
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• pp.5-23
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• 2014

The possibility of non-destructive inspection glass beads for verification. Conduct a comparative analysis of the Chungcheong area with glass beads excavated Age-specific characteristics of the glass beads shall be classified by region. Trace amounts of ingredients such as CaO, $Al_2O_3$ (stabilizer), MgO, the difference is negligible. $SiO_2$ (subjects), $Na_2O$ (flux) analysis and the difference between the values was greater than in the other ingredients. Composition differences occurred rough surface to a non-uniform cross-section analysis is considered. Minimize the error value, such as the surface of carbon-coated Study, there are additional requirements. Produced at the time of the social and cultural characteristics of ancient glass and important archaeological materials, and to inform the process of cultural exchange between each region in the production of glass technology era according to the level of science and technology, arts and crafts, can be identified.

• Structural Engineering and Mechanics
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• v.6 no.3
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• pp.259-274
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• 1998

The test results from non-destructive and destructive field testing of a three-span deteriorated reinforced concrete slab bridge are used as a vehicle to examine the reliability of available tools for finite-element analysis of in-situ structures. Issues related to geometric modeling of members and connections, material models, and failure criteria are discussed. The results indicate that current material models and failure criteria are adequate, although lack of inelastic out-of-plane shear response in most nonlinear shell elements is a major shortcoming that needs to be resolved. With proper geometric modeling, it is possible to adequately correlate the measured global, regional, and local responses at all limit states. However, modeling of less understood mechanisms, such as slab-abutment connections, may need to be finalized through a system identification technique. In absence of the experimental data necessary for this purpose, upper and lower bounds of only global responses can be computed reliably. The studies reaffirm that success of finite-element models has to be assessed collectively with reference to all responses and not just a few global measurements.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.2
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• pp.81-86
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• 2005

This paper proposes a non-destructive ESPI technique to quantitatively evaluate defects inside a semiconductor package. The inspection system consists of the ESPI system, a thermal loading system and an adiabatic chamber. The technique is high feasibility for non-destructive testing of a semiconductor and overcomes the weaknesses of previous techniques, such as time-consumption and difficult quantitative evaluation. Most defects are classified as delamination defects, resulting from the insufficient adhesive strength between layers and from non-homogeneous heat spread. Ninety percent of the tested samples had delamination defects which originated at the corner of the chip and nay be related to heat spread design.